Flexible joint for artificial limbs



June 15, 1948. J, H, MA1-H15 2,443,356 I FLEXIBLE JOINT FO ARTIFICIAL LIMBS Filed April 2, 1946 l im .Mmmm

Patented June 15, 1948 UNITED STATES PATENT vOFFICE FLEXIBLE JOINT FOR ARTIFICIAL LIMBS John H. Mathis, Temple, Tex.

Application April 2, 1946, Serial No. 658,958

2 Claims. 1

This invention relates to an artificial limb, more particularly to the ankle joint therefor.

The primary object of the invention is to provide a flexible joint between the foot and shin members of an artificial leg of such a iiexible nature that it will closely resemble the ankle joint of a human foot.

Another object is to provide a joint of such a character that it will absorb the shock of step ping or walking.

The invention will be clearly understood to those skilled in the art by reference to the accompanying drawings in which;

Figure 1 is a side elevation of the ankle and foot;

Figure 2 is a cross section of the heel as taken on line 2-2 of Figure 1.

Figure 3 is an end elevational view of the spring when not under pressure.

Figure 4 is the same as Figure 3, but showing the spring under pressure.

In the preferred form of my invention as illustrated, the shin member I and foot member 2 are connected through the medium of an intermediate block 3 by means of spring members connected to various portions of the leg and foot.

All of the springs are of the same general conguration, and a description of one will suce to describe all of the springs.

Mounted on the transverse and horizontal axis and taking the place of the ankle bone of the human foot, is a spring element 4. Referring to Figure 3, it will be noted that the spring element 4 comprises a pair of plate-like bowed members 5 and 6 with their apices adjacent. The corresponding ends of the springs 5 and 6 lie between a central triangular-shaped member 'I and a slightly larger open triangular member 8 which cverlies the ends of the members 5 and 6. Bolts 9 extend through the side legs of the triangularshaped members 'I and 8 and the ends of the springs which lie against the side faces of the members 'I and 8 thus connecting the springs to the various parts comprising the artificial foot and leg. The openings through which the bolts 9 pass are all of the same size, so that the ends of the springs 5 and 6 are held against sliding. All stress and strain upon the springs 5 and 6 are taken up by their bending action. The springs 5 and B which have been described as bowed, are more nearly oi.' a concavo-convex formation.

The spring element 4 connects the intermediate block 3 to the shin member l, and, as stated, is mounted on a transverse and horizontal axis.

Spring elements 4 and 4" connect the inter- 2 mediate block 3 to the foot 2 and are mounted in recesses provided in the two members. These elements are at right angles to the element 4 and to the front and rear of that element, but in dif ferent horizontal plane.

The intermediate block 3 is cut so that it will fit into the space formed in the foot portion 2. However, it is spaced from the shin member l. Blocks I0 and II of rubber or the like, are placed between the shin and intermediate block in the front and rear portions for the purpose of further reducing shock. A covering I2 of leather or the like, is placed over the front of the joint between the shin and intermediate block. However, the covering may be placed over the entire joint so as to prevent injury to apparel which may be placed over the foot.

A V-shaped recess I3 is formed in the foot between the instep I4 and toe portion I5. This recess has a V-shaped block of rubber I6 which is held therein by a flexible cover I1. The rubber block mounted between the instep and toe portions of the foot aid in giving flexibility to the foot when walking.

When in use, all of the springs 5 and 6 will flex to the approximate position shown in Figure 4. The springs 5 and 6 of the spring element 4 will bend on a line extending transversely and horizontally of the foot, while those of the elements 4 and 4" will bend on a line extending longitudinally of the foot. When the wearer is Walking and the foot and leg are at an acute angle to each other, the spring 5 will bend rearwardly while the spring 6 will have a tendency to straighten. This same action will occur in the element 4 and 4 depending upon the side to which the foot is rocked. Thus it will be seen that the three spring elements together with the rubber blocks I0 and II will remove all shock coincident with use of the leg.

By mounting the three springs in the manner shown, universal movement of the foot is allowed so that the ankle joint closely approximates that of the human foot. This will aid anyone in using the foot in walking on uneven surfaces.

While there is shown and described one form of the ankle joint, it is well understood by those skilled in the art that various changes may be made, which are within the scope of the appended claims.

I claim:

1. An artificial leg, a shin member and a foot member, a block interposed between the members, a spring connecting the shin member to the block and a second spring at an angle to the 3 first-named spring, connecting the block to the foot member.

2. An artificial leg comprising shin and foot members, a, block between the members, a spring connecting the shin member and the block, a 5

REFERENCES CITED The following references are of recordiin-the le of this patent:

Number Number UNITED STATES PATENTS Name Date Lewis May 29, 1883 Hagen Jan. 18, 1898 Pold Oct. 13, 1903 FOREIGN PATENTS Country Date Germany .Jan. 10, 1920 

